Thanks for the feedback!
If you haven't tried using the examine feature, it lists all of an enemy's special properties (well, except for a few last minute behavioral changes to spiders). I do think there's room for communicating more information without relying on examine, though. Poison is probably the worst offender here. The only place it's explained is if you examine a creature which is already afflicted (potentially yourself). A message log hint like "You can remove the poisoned condition by waiting" the first time per game you're poisoned would probably help a lot. Also, at one point I planned on including static properties like "flying" in the monster list but didn't actually end up implementing it and I can see it helping as a reminder/hint of what the enemy does.
I don't really have an easy solution for diagonal movement clarity, though. I'd probably have to rework my entire UI stack, which I'd like to do anyways at some point though not necessarily for this game specifically.
In any case, I probably won't update the game until judging is over, but I've added some hints about using examine and what status conditions do to the game page.